In a dry electrophotographic process, i.e. xerography, the following steps are usually involved:
(1) Sensitizing the xerographic plate by a corona discharge. PA1 (2) Exposing the plate to form an electrostatic latent image. PA1 (3) Developing the latent image with fine particles, i.e. developing powder. PA1 (4) Transferring the developed image to another material such as paper, and PA1 (5) Fixing the image by fusing. PA1 (1) Magnetizing an image formed on a printing master which has been prepared by applying a magnetic ink to paper. PA1 (2) Developing the magnetized image with fine particles, i.e. developing powder. PA1 (3) Transferring the developed image to another material such as paper, and PA1 (4) Fixing the image by fusing.
In a magnetic printing process, the following steps are usually involved:
In the dry electrophotographic process, there are used developing powders comprising a mixture of resins and coloring matters such as dyestuffs or pigments. In the magnetic printing process, there are used developing powders comprising a mixture of resins, coloring matters such as dyestuffs or pigments, and ferromagnetic powders such as magnetic iron oxide.
The resins used in preparing the developing powders as shown above include, for example, acrylic resin, epoxy resin, alkyd resin, and a mixture of polyvinylbutyral and rosin-modified phenol-formaldehyde resin.
In the event the conventional developing powders are used, the developed image can be fixed to an image-forming substrate such as paper by heating or by applying solvent vapor. In these processes, heating rolls or means for generating the solvent vapor are required, respectively.
It is an object of the present invention to provide developing powders which can be fixed to an image-forming substrate such as paper by applying pressure only, without heating or applying solvent vapor.